I have P type boron doped wafers which I a) do a piranha soak b) do an oxygen plasma treatment for 2 minutes c) dehydrate in 200 degree oven for 30 minutes.
I spin coat using SU-8 2075 in two coats as my features are large/tall. So I soft bake coat 1 (100um tall) at 65 degrees for 5 minutes followed by 20 minutes at 95 degrees and repeat for a coat 2 (100um tall) so that my features are 200um high.
I post-bake 5 minutes and 12 minutes, 65 and 95 degrees respectively and develop in EC solvent for 10 minutes using a sonicator as this is necessary to lift the SU-8 off from some of the smaller features. I then hard bake at 150 degrees for ten minutes using a gentle incline and decline to/from temperature. I gleaned this information from the official protocol.
I cannot see what I am doing wrong but my features almost always detach in areas. Help anyone?
Try a longer softbake. Since you have a coating that is 200 microns you'll need to make that bake longer the get the solvent baked out. Residual solvent may act as a photoinhibitor and cause cross-linking to be asymmetric which will result in a high film stress that cannot be relaxed out by baking.
You may also want to try spray developing instead of sonication.
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